How to tell if a 2 digit number is PRIME in 1 SECOND! | FUN Number Theory!

We explain a simple mental math trick to decide if a two digit number is prime instantaneously! We first prove (and explain) a basic statement (in number theory) on prime factors of two digit numbers, in an accessible way. We then explain divisibility tests by 2, 3, 5, and 7. Finally, we give some random two digit numbers, and explain how to instantaneously decide if they are prime numbers. The video is designed for people at all levels of math who know what prime numbers are, and are familiar with some basic algebra and divisibility rules (by small numbers like 2, 3 and 5). For example, this video would be interesting also to students interested in math puzzles, creative math tricks, competition math, math olympiads, math proofs, number theory etc. If you enjoy this video, I would love if you could please like ✅ , subscribe 🎉, and share ⏩ with students, classmates, friends and family - it means so much to help support me in my goal of creating elite infinite free accessible math education worldwide! 😊 If you would like to support my channel beyond this (which of course would mean so much to me 🤗), please check out my "Patreon" page! The contributions here make a world of difference to helping me free up time to produce as much math content as possible (I currently do everything on my own), and there are also exclusive perks available when you signup (e.g., exclusive access to a private Discord server to chat and discuss math with me and other members, insider knowledge on my future YouTube content creation, priority replies to YouTube comments, public acknowledgements as a valued sponsor, a personalized thank you message etc.)! 😊 Become a Patreon Member 🤩:   / mathmasterywithamitesh   A HUGE thank you SO much to Stephan for their continued support of the channel as a Ruby Member, and Alex, Nathan, and Trang for their continued support of the channel as Gold Members!! 🎊 My Channel Membership 🥇:    / @mathmasterywithamitesh   A HUGE thank you SO much to EnejotaNeyJr, Aman, Rob and Shabeed for their continued support of the channel as Silver Members!! 🎉 You can also follow me on Instagram!   / math_mastery_with_amitesh